1. Field of the Invention
The present invention relates to a transparent transistor, and particularly, to a structure of a transparent transistor having high transmittance.
2. Discussion of Related Art
To manufacture a transparent transistor, all materials constituting the transistor, for example, a semiconductor, an insulator and a metal, should be transparent. Insulators are generally transparent in a visible light range, and in the case of semiconductor, oxide semiconductors, which have been recently used for transistors, are transparent. In the case of metal, since ITOs have the lowest resistance of transparent metals, ITOs are generally used for transistors.
However, as displays become larger, an interconnection length increases and electric conductivity of ITO is insufficient to be applied to a high-performance transparent circuit. Accordingly, a metal is used as an auxiliary interconnection to decrease an electrical resistance of the interconnection. However, in this case, an additional process is required and overall transmittance decreases because of the opaque metal interconnection.
Meanwhile, when a multi-layered transparent conductive layer is applied to a thin film transistor using a common manufacturing process, problems can be caused by etching of a multi-layered thin film, a contact resistance between source and drain electrodes and a semiconductor, and additional processes for deposition of the multi-layered thin film.